Mobile IPv6 (MIPv6) is an implementation of Internet Protocol version 6 (IPv6) that supports the exchange of data in a packet switched internetwork. MIPv6 allows an IPv6 node to be mobile, i.e., arbitrarily move about an IPv6 network while maintaining existing connections as well as reachability using an IPv6 address.
FIG. 1 illustrates an internetwork 100. Internetwork 100 includes a mobile node (MN) 105 that communicates with a host 110, for example. Communications between MN 105 and host 110 go through a home agent (HA) 115. All traffic to and from MN 105 should go through HA 115. MN 105 registers its current location, e.g., its IP address, with HA 115. However, prior to providing HA 115 with its own IP address, MN 105 may need to obtain the IP address of HA 115. Please refer to “Mobile IPv6 Bootstrapping in Split Scenario,” Giaretta, G., Kempf, J., and V. Devarapalli, RFC 5026, October 2007, for a detailed discussion of the registration of a MN to a HA, which is incorporated herein by reference.
Generally, there may be multiple HAs that may serve as HA for a particular MN. A particular HA may be selected out of the multiple HAs based on factors such as proximity to either a MN or its host, HA response times, HA load, and so forth. Once a HA has been selected to be the HA of the MN, a sequence of messages may be exchanged to complete the registration process, with the exact sequence being dependent on the actual mechanism being used to perform the registration.
Typically, once the MN has registered with the HA, the MN may remain with the HA until it is powered down, leaves the internetwork, or so forth. However, it may be necessary for the HA of the MN to redirect the MN to a different HA. The HA may redirect the MN to the different HA due to factors such as overloading, load balancing, scheduled downtime, occurrence of unexpected fault or error, and so forth.
In “Mobility Header Home Agent Switch Message,” Haley, B., Devarapalli, V., Deng, H., and J. Kempf, RFC 5142, January 2008, which is incorporated herein by reference, a mechanism called Home Agent Switch is proposed to allow for a HA to handoff some of its MNs to other HAs. A Home Agent Switch message may be used as a handoff notification between the HA and a MN. However, the Home Agent Switch mechanism may only be used after a binding cache has been created at the HA for the MN. The necessity of creating the binding cache may place additional burdens on the HA, which may already be overloaded or faulty.